Non-ambulatory patients who must be supported and moved in a patient facility such as a hospital or a nursing home present substantial challenges when a course of treatment for such patients calls for movement from one location to another. A patient may, for example, need to be moved from a hospital bed, which must remain in the patient's room, to a stretcher and then from the stretcher to a treatment location such as a surgical table in an operating room. Following treatment the reverse patient handling sequence must occur; i.e.: the patient must be moved from the surgical table, which remains in the operating room, to a stretcher which travels to the patient's hospital room, and then from the stretcher back onto the bed in the hospital room.
In a very large percentage of such occurrences the patient must be handled in a fashion which requires only a minimum of movement of the patient with respect to his or her supporting surface. In the case of a patient being returned to a hospital room following surgery, for example, the patient's body may not be able to withstand the stresses and strains of being lifted from a stretcher to the bed when one or even several hospital personnel combine their efforts to make such a transfer.
The same challenge of moving a patient with minimum handling exists in non-surgical settings as well. The bariatric patient is a prime and very common example. When such a patient is categorized as morbidly obese, transfers present difficulties for both the patient and the care facility staff. While no exact definition of morbid obesity is universally recognized, many hospitals and other treatment facilities consider a person who weighs about 350 pounds or more to fall within that definition.
Movement of a morbidly obese person often requires the hospital staff to physically lift and/or slide the patient from an at rest position on a hospital bed to an at rest position on a stretcher a total of four times to complete a single treatment cycle, such as surgery. The staff must perform the task of lifting and/or sliding such a patient because in nearly all instances the patient, due to the physical condition of obesity and/or illness, simply cannot do the task alone. The manipulation of such a person requires a plurality of hospital staff since such manipulation is impossible to perform by a single person such as a floor nurse assigned to the patient's room. As a consequence such transfers must be planned in advance for a specific time and a number of hospital staff must be notified and arrange their schedules so that all staff will be available at the exact same time whereby the task, which may take only a few minutes once the manpower is available, can be carried out in a timely fashion. In some instances, half dozen or more such persons may need to be assembled for this movement. Instances have been known in which a morbidly obese patient has required twelve persons to enable the transfer of such a patient. Gathering together such a large number of people four times at often uncertain intervals to provide but a single cycle of treatment to a patient raises obvious logistical problems and, in addition, erodes the quality of care the facility can render by reason of the application of such a large number of personnel to deal with but a single patient treatment episode.
While morbidly obese patients represent an extreme end of the spectrum, it should be understood that making any transfer, lateral or otherwise, of any patient or adjustment to a patient's position can induce stress and/or strain and potential injury to a caregiver.
A further drawback to such a patient handling system as above described is that, even with the best intentioned and caring of staff, the patient very often suffers substantial discomfort. The simple act of sliding a patient over a flat surface can be very painful to a patient who has had surgical incisions which are far from healed, for example.
An attempt has been made to overcome the above described problems by the use of an air mattress onto which the patient is placed while in bed and which is then placed onto a stretcher. A problem common to all such devices however is that invariably the air mattress has the general characteristic of a balloon in the sense that when one area is indented another remote area will bulge, thus creating an unstable condition. If for example a stretcher carrying an obese person makes a sharp turn during a trip to or from a treatment location, such an obese person will tend to roll toward the outside of the turn due to the instability of such a conventional air mattress. The more the patient rolls, the more that that portion of the edge of the mattress toward which the rolling movement occurs will depress, and the greater will be the expansion of the mattress on the other side of the patient. In effect, the conventional mattress reinforces the undesirable rolling movement and hence can be termed to be unstable. Since much of the time the patient is incapable of stopping the rolling action alone the patient may roll off the stretcher onto the floor with disastrous consequences. Indeed, even in the instance of a patient who is capable of moving themselves to some degree about their longitudinal body axis the same disastrous result may occur because the displacement of air from one edge portion of the mattress to the opposite edge portion creates in effect a tipping cradle. Only if the patient lies perfectly flat and perfectly still on the stretcher and no roadway depressions or blocking objects, such as excess hospital beds stored in a hallway, are encountered can the probabilities of an accident be lessened.
Planar air pallets and air-bearing patient movers of the type disclosed in U.S. Pat. No. 3,948,344 entitled “LOW COST PLANAR AIR PALLET MATERIAL HANDLING SYSTEM” and U.S. Pat. No. 4,272,856 entitled “DISPOSABLE AIR-BEARING PATIENT MOVER AND VALVE EMPLOYED THEREIN” employ at least one thin, flexible bottom sheet for partially defining a plenum chamber, which is perforated by way of small, closely spaced pinholes over a surface area defined by the imprint of the load, which pinholes face an underlying fixed, generally planar support surface. The pinholes open unrestrictedly to the interior of the plenum chamber and to the planar support surface. When the plenum chamber is pressurized by low pressure air, the air initially jacks the load upwardly above the thin, flexible sheet, then air escapes under pressure through the minute pinholes and creates a frictionless air bearing of relatively small height between the underlying support surface and the bottom of the perforated flexible sheet.
In all air pallets, including patient movers, it is necessary to provide controlled pillowing of the thin, flexible sheet material, particularly outside the perforated surface area of that sheet to initially jack the load above the flexible sheet prior to the creation of the frictionless air bearing and to insure the ability of the air pallet to ride over surface projections on the underlying support surface. Means must also be provided within the air pallet to prevent ballooning of the thin, flexible sheet or flexible sheets defining the plenum chamber whereby the plenum chamber takes a circular or near circular vertical cross-section, the result of which could be the tilting or rolling of the load off the top of the air pallet. Further, when the load rests on the air pallet, prior to the pressurization of the plenum chamber the load tends to press the perforated flexible sheet into contact with the underlying support surface which prevents the entry of air under light pressure into the plenum chamber.
In the development of the air pallets, and in particular air bearing patient movers as a form of such air pallets as exemplified by U.S. Pat. No. 3,948,344, a corrugated sheet such as sheet within the single chamber functioning as a plenum chamber in a patient mover formed by two superimposed thin, flexible sheets in U.S. Pat. No. 4,272,856 may constitute both a unitary air dispersion means and a semi-rigid backing member (if needed). The semi-rigid backing member may comprise a semi-rigid sheet inserted within a cavity formed between the top thin, flexible sheet and an intermediate thin, flexible sheet. Alternatively, the backing member may be formed of a series of transversely linked air pressurized tubes formed by sealing off parallel, laterally adjacent longitudinal sections of the top sheet and the intermediate sheet. Such tubes may be completely sealed and air pressurized through valves. In a flow-through system, the pressurized air forming the air bearing passes first through parallel, transversely linked tubes defined by the top and intermediate sheets and then into the plenum chamber defined by the intermediate sheet and the bottom sheet with the bottom sheet bearing the pattern of perforations over the foot print of the load. U.S. Pat. No. 4,528,704 entitled “SEMI-RIGID AIR PALLET TYPE PATIENT MOVER” is directed to such air pallets.
In the field of air pallets and particularly of the patient mover type those patient movers formed of multiple, thermal bonded or stitched sheets of thin, flexible sheet material which incorporate a rigid or a semi-rigid sheet as the load backing member are not universally employed in health care treatment facilities. The existence of the rigid or semi-rigid sheet carried within a pocket or cavity defined by two thin, flexible sheets renders the assembly bulky, and adds considerably to the weight of the same. While such patient mover may perform extremely well at a certain hospital station or treatment area such as facilitating patient movement onto and from an X-ray table, the patient mover remains at the area and is unlikely to be employed in moving the patient to and from the hospital bed remote from the X-ray area since hospital personnel resist transporting such patient mover from location to location.
There are significant differences between the rigid back air pallet and the flexible or air chamber-type air pallet with a load that can flex. In the development of air pallets and air pallet-type patient movers utilizing a thin, flexible bottom sheet partially defining a plenum chamber and being perforated by way of thousands of small, closely spaced pinholes over the surface area defined by the imprint of the load and which open unrestrictedly to the interior or the plenum chamber and to an underlying planar support surface, such air pallets and air pallet-type patient movers have generally employed a rigid backing member starting with U.S. Pat. No. 3,948,344.
Certain structural features and parameters with respect thereto play a very important part in the successful operation of an air pallet having a rigid backing member. The key for successful movement of a load on a developed air film by air escape from the perforations is to make the air work on the load and to control the action of the air in doing that job. By matching the footprint of the load to that of the plenum chamber pattern area of perforations, thus generally matching the area of the developed air film to that of the load, the air pallet with the plenum chamber pressurized will jack the load, create the air bearing and permit the load to be stably moved on the air pallet.
Successful operation of rigid backing surface type air pallets requires controlled jacking, controlled pillowing and anti-ballooning. Control of load distribution may be achieved by the use of a rigid backing member such as a board or sheet as part of the plenum chamber, or within a separate chamber supporting the load but overlying the plenum chamber. The rigid backing member distributes the load mass balanced equally over the area of the plenum chamber footprint. The control of the plenum chamber can be performed in several ways and a properly designed plenum chamber can affect several of the control functions, i.e., jacking, pillowing and ballooning.
In U.S. Pat. No. 4,272,856 for an operative air pallet-type patient mover, pillowing is controlled by having the pattern of perforations extending to the edge of the plenum chamber and the sides of the plenum chamber are purposely designed to match the head and torso of the patient from the shoulders to the hip, where the load mass of the patient is concentrated. Certain parameters with respect to the load, i.e., weight, patient size and load footprint, are matched to the plenum chamber area, otherwise the unit will not work or work poorly.
An air pallet plenum chamber upon pressurization tends to take a shape resulting in lateral reduction of the plenum chamber air film footprint. Since the patient's body is movable and flexes, this creates significant problems. Not only is such load not rigid, but the top flexible sheet is not a rigid member and, indeed nothing structurally is rigid. Further, only the torso and head is supported by the plenum chamber (i.e., jacked up), and the rest of the body (legs, arms, etc.) simply drag along with the air pallet once an air bearing or air film is created by escape of air through the perforations within the thin, flexible bottom sheet. If the patient has a broken limb, this is not a small problem but a catastrophe. Patient loading on the air pallet and removal from the air pallet produces significant problems. Thus, the ability to create a patient mover having a size to fit the patient, the bed, the portable gurney and a procedure table such as an operating table was quite desirable.
These problems led initially to developments exemplified by U.S. Pat. Nos. 4,528,704 and 4,686,719. The key to solving most of the problem areas seemed to lie in the utilization of a rigid backing member, but a rigid backing member made it more difficult to place the patient on the patient mover. The patient has to be physically log-rolled, and almost face down to one side so that the rigid backing member is juxtapositioned to the patient, and the patient is then rolled back over so that the patient ends up supine on the patient mover. This procedure follows that of placing the sheet under a patient when on a hospital bed, but a sheet can be folded in half and slid under the patient without turning their body excessively to one side. Such is not so for a patient mover having a rigid backing member.
Other attempts have included using a flexible pad in place of the rigid backing member. Generally at the same time, there was considered the separation of the jacking action from that of creation of the frictionless air film. This led to the development of stacked tubes, one functioning as a pure jacking chamber, and the second as a combined jacking chamber and plenum chamber. The result is a gas pressurized jacking structure with improved load stability, in which the same compressed air pressurizing the upper chamber through a dynamic flowthrough arrangement, functions in passing through the pin hole perforations of the plenum chamber thin, flexible bottom sheet, to create the air film.
In air chamber-type air patient movers, a phenomenon was experienced as the result of air pressurization of the tubular chambers formed by sealed sections of the upper two thin, flexible sheets and the air pressurization of the plenum chamber underlying all of the upper row of tubes common to the intermediate thin, flexible sheet of said row of tubes. The entire unit took on a full vertical circular cross-section and attempted to approach a cylinder, which was termed “hot dogging”. During hot dogging, the plenum chamber takes on an almost circular cross-section in a plane at right angles to the longitudinal axis of the series of joined tubes formed by the top thin, flexible sheet, the intermediate thin, flexible sheet and the bottom thin, flexible sheet of the air pallet. A plenum chamber is formed between the thin, flexible intermediate sheet and bottom sheet with the bottom sheet having literally thousands of closely spaced pinholes through which air escapes from the plenum chamber to form an air film or air bearing between the thin, flexible bottom sheet and the generally rigid, planar surface beneath. Each of the transverse seal lines joining the top and intermediate sheets, which together form individual air pressurizable chambers or tubes, function as hinging areas between adjacent tubes. The result of such hinging is the high instability for any load in contact with the exterior of the top thin, flexible sheet. It is further seem that the single large sectional area formed by the plenum chamber is without a means for controlling hot dogging and is thus extremely susceptible to this instability problem.
In U.S. Pat. No. 5,067,189 entitled AIR CHAMBER TYPE PATIENT MOVER AIR PALLET WITH MULTIPLE CONTROL FEATURES, the foregoing described problems of over pressurization causing instability of the patient mover and the load, enlargement of the underlying plenum chamber to an almost vertical circular cross-section, i.e. “hot dogging”, during pressurization, the requirement for a rigid or semi-rigid backing member to prevent “hinging” between individual longitudinal chambers or tubes for supporting the load, and the point load grounding out on the underlying support surface due to load shifting were tentatively resolved. During the course of improving the earlier air pallet patient movers of the air chamber type, it was found that all of the recited problems with prior types of inflatable air pallets were substantially interrelated, as well as the discovery of an additional structural problem described as the reduction or shrinkage of the lateral dimension of the air pallet. U.S. Pat. No. 5,067,189 reduces the recited problems through a novel interrelated structure. In lieu of a rigid or semi-rigid backing member, a series of stacked rows of pressurized chambers or tubes have been utilized which create a pre-determined air dispersion which, in concert with the air dispersion in the underlying plenum chamber, properly jacks the load, e.g. a patient, and maintains the flexible backing surface (the stacked rows of tubes or chambers) in a planar direction generally parallel to the underlying developed air film. Simultaneously, the plenum chamber is inflated and through the underlying perforations creates an air film between the air pallet and the fixed support surface, but only in an area which generally matches the footprint of the load. Further, the inflation of the plenum chamber within the parameters set forth in U.S. Pat. No. 5,067,189 creates a sufficient pillowing means to permit the air pallet to accommodate surface irregularities and move the load on the developed air film without bottoming out, for example grounding, and without the bottom flexible sheet ballooning outward. This is accomplished through a series of vertical and oblique ties which restrain the separation of an intermediate sheet forming the bottom of the linked rows of chambers or tubes and the underlying bottom sheet of the plenum chamber from moving outward one from the other beyond a pre-determined distance. These ties (or stringers) in combination with the stacked rows of chambers or tubes prevent “hot dogging” of the air pallet when inflated, tend to reduce lateral shrinkage of the air pallet because of its anti-hot dogging and anti-ballooning effect, and increase the ability of the air pallet to accommodate surface irregularities when in motion so as not to create a point load problem, all of which increase the load stability of the particular air pallet.
The above various configurations and designs of air bearing pallets and patient movers have overcome or attempted to overcome, a number of the stability issues. However, there exists a further problem with air bearing pallets, when these devices are being transferred between two locations which are separated by a void region. The air being expelled from the air bearing pallet in order to generate the air film for ease of movement, can become less effective and may be substantially non-functional at this void location due to air pressure loss. This phenomenon may result in the grounding of load for example a patient, during transfer over this void region.
Therefore there is a need for a new air bearing pallet which can mitigate the potential loss of operation of the air bearing pallet during transfer over separations or void regions.
This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.